Tailing copper cobalt sulfide particle-decorated tube-like structure as efficient active material of battery supercapacitor hybrid

Copper cobalt sulfide (CuCo₂S₄) has received intensive attentions as one of effective battery-type materials of battery supercapacitor hybrids (BSH), because of numerous redox states and large conductivity. Morphology has been widely reported to play important roles on energy storage ability. Tube-like structure is beneficial for providing large surface area at inner/outer surface, and efficient charge transfer paths in one-dimensional directions. In this study, the CuCo₂S₄ particle-decorated tube-like structure is firstly designed on nickel foam via the hydrothermal process at different temperatures. The effects on morphology, composition and electrochemical performance are examined. The CuCo₂S₄ synthesized at 160 °C shows the most uniform rod size and regularly distributed particles on surface. The highest specific capacitance (C_F) of 831.7 F/g corresponding to the capacity of 115.6 mAh/g is achieved for the optimal CuCo₂S₄ electrode, due to the largest electrochemical surface area with multiple active sites. A BSH is fabricated by using the CuCo₂S₄ positive electrode and the activated carbon negative electrode. A wide potential window of 1.5 V and the maximum energy density of 32.1 Wh/kg at power density of 1.1 kW/kg are achieved. The C_F retention of 78.8% and Coulombic efficiency of 95.5% are also attained after 10,000 charge/discharge cycles for the BSH.